The field of the invention relates to microsurgical equipment, and particularly to apparatus for providing irrigation to a surgical situs and aspiration for removing tissue and fluid therefrom.
Microsurgical systems are used for performing many operations today, including ophthalmic surgery. Systems for removing cataracts, for example, typically include a cutting probe and associated aspiration device for removing mascerated tissue to a collection vessel. An irrigation supply is also provided to replace the fluid removed through aspiration. The cutting probe and associated irrigation/aspiration lines are often mounted to the same handpiece which is in turn connected to a machine for controlling the cutting (or emulsifying), aspiration and irrigation procedures. Such machines include irrigation/aspiration manifolds including a roller pump and vacuum source for controlling aspiration, and valve means for controlling irrigation.
The irrigation/aspiration manifolds of most modern systems include disposable cassettes which maintain the irrigation and aspiration tubing in the desired positions with respect to the machine. U.S. Pat. Nos. 4,493,695, 4,626,248, 4,627,833, 4,713,051 and 4,735,558 disclose various cassettes and mounting assemblies therefor which have been proposed for use in ophthalmic surgery systems.
One of the problems encountered in the use of some cassettes is the unintentional pinching of the flexible aspiration tube as the roller pump operates. The roller pump includes a plurality of rollers which are rotated about an axis and bear against the tube. In addition to the desired occlusion of the tube between the rollers and a selected portion of the cassette manifold, the tube tends to be pulled in the direction of rotation of the pump rollers. The tube may accordingly become partially or completely occluded at the point where it is pulled against the manifold.
Another difficulty with respect to cassettes is in mounting them to the emulsifier/aspirator unit. Such units typically include horizontally disposed slots for receiving the cassettes. Latch mechanisms are provided for maintaining the cassette in the desired position with respect to the pump rollers, vacuum source and irrigation control means. Some cassette receptacles require the user to push the cassette into the correct position within the slot. This can sometimes result in improper seating if the proper force is not applied.
Another type of latching mechanism includes a pair of spring-loaded cams which resiliently urge the cassette towards the pump rollers. The cassette will accordingly tend to oscillate within the slot when the roller pump is actuated.